Induvidual search for every column not working, why not?

Induvidual search for every column not working, why not?

On my code below I am trying to apply a search to every column in the header, I am pretty sure the only thing not working is the that.search(this.value) since every time I write on the input boxes of every column the column that i just finished writing on is ordered on 'asc', so .order('asc') its working. Could anybody help me figure out why isn't .search(this.value) isn't working?